SU1307040A1 - Method of constructing foundation on sagging loess soil - Google Patents

Abstract

The invention relates to a method for the construction of foundations on loess subsidence soils and allows the foundation to be protected from seismic effects. In the subsidence of the soil 1 form an array of 2 of the fixed soil, and around the array 2 - adjacent to the holder 4 of the stabilized soil. The sleeve 4 is formed by injecting into the soil weak alkaline solutions, preferably solutions of ammonia and sodium silicate of 3 to 9 ° C / d concentration. The concentration of the sodium silicate solution is increased in the direction from the upper end of the holder 4 to the lower one, and the holder 4 is made of a thickness equal to 0.5-3.0 of the width of the array 2. 1 h. item f-ly, 2 ill. with A-A (L oo o o 4 Fig. 2

Description

The invention relates to construction mainly in seismic areas and can be used in foundation engineering and hydraulic engineering to eliminate subsidence in loessal soils.

The aim of the invention is to protect the foundation against seismic effects.

FIG. 1 shows a foundation, a plan view; in fig. 2 shows section A-A in FIG. one.

The described method of building a foundation on loess subsidence soil 1 includes the formation of array 2 of fixed soil in the subsidence depth of the soil, placing base plate 3 on array 2 and creating 4 stabilizer soil around array 2 by injection of weak alkaline solutions, preferably on a base ammonia and sodium silicate 3–9% concentration. The concentration of the sodium silicate solution is increased in the direction from the upper end of the holder 4 to its lower end. As a result, underlying soils may experience greater pressure. The sleeve 4 is made depending on the thickness of the sinking layer with a thickness of 0.5-3.0 width of array 2 from the fixed ground. The proposed method can be used both in the construction of column and strip foundations.

Example. During the construction of the foundation according to the proposed method, an array of fixed soil is formed over the area of the foundation; injecting solutions based on sodium silicate with a density of more than 1.1 g / cm. Then, around the array of fixed soil, a cage of stabilized soil is made, injecting into the loess soil a weakly alkaline solution with a content of sodium silicate and ammonia less, increasing the solution concentration from top to bottom from 3 to 9%. After the pit passages set the base plate.

The loess soil of the natural structure was destroyed under the following stresses; soil with a diffusion complex of water — at 0.22–0.38 MPa, with capillary and gravitational — when saturated with water, the Initial sinking pressure of the soil is 0.12 MPa, the relative subsidence is 0.05.

In tab. Figure 1 shows the stresses arising from the passage of a seismic wave in loess soils.

Table 1

Score, MLA, in the ground with a water complex

diffusion capillary and gravitational

80,073-0,1440,185-0,368

90,145-0,2830,369-0,736

In tab. Figure 2 shows the stresses at which the ground is broken, after consolidation and stabilization.

table 2

State, MPa, in the ground with a complex of water

soil.-...-..--. -..- -.-..- .. diffusion capillary

and gravitational

At the same time, the loess ones were unstable under a load of up to 0.6 MPa and were not soaked in water.

Thus, the soil of the cage does not sag and does not collapse at stresses arising from a seismic wave, which leads to the exclusion of the impact from the surrounding array of soil on the foundation.

Claims (2)

1. A method for building a foundation on loess subsiding soils, including the formation of a mass of fixed soil in the subsidence depth of the soil mass and placement on it of a foundation slab, characterized in that, in order to ensure the protection of the foundation from seismic effects, around the array of fixed soil they form a holder of stabilized soil by injection into the surrounding soil of weak claim 1, Christmas-tree solutions. 2. A method according to claim 1, characterized in that, during the formation of the cage, ammonia and sodium silicate solutions are injected into the soil at a concentration of 3-9%, and the concentration of sodium bicate sodium solution is increased in direction from the upper end of the cage to its bottom the end face, and the two sides are made with a thickness equal to 0.5-3.0 width of the array of fixed soil.  i. Jl Fig